Liquid extractor



June 13, 1967 R. E. TREYBAL LIQUID EXTRACTOR 4 Sheets-Sheet 1 Filed Sept. 1'7, 1965 R. E. TREYBAL LIQUID EXTRACTOR June 13, 1967 Fild Sept.

4 Sheets-Sheet 2 June 13,

7 R. E. TREYBAL 3,325,255.

LIQUID EXTRACTOR Filed Sept. 17, 1963 4 Shets-Sheet June 13, 1967 R. E. TREYBAL 3,325,255

LIQUID EXTRACTOR Filed Sept. 17, 1963 4 Sheets-Sheet 4 United States Patent 3,325,255 LIQUID EXTRACTOR Robert E. Treyhal, 145 W. Hartsdale Ava, Hartsdale, N.Y. 10530 Filed Sept. 17, 1963, Ser. No. 309,520 7 Claims. (Cl. 23--270.5)

This invention relates generally to apparatus for producing countercurrent contact between two substantially immiscible liquids having different densities, and more particularly to apparatus for continuously carrying out a multi-stage, countercurrent contact of two immiscible, or substantially immiscible, liquids of different densities for such purposes as withdrawing one or more components from one liquid by contacting it with another liquid as, for example, in washing or in chemical treating operations, or for some other purpose.

Devices of the type with which this invention is concerned are, in the parlance of the art, commonly called liquid extractors. Such devices may be used for the separation of the components of a solution by the process known as liquid extraction, liquid-liquid extraction or solvent extraction; these terms sometimes referring to single solvent extraction or to fractional or double solvent extraction. Other purposes of such devices include transfer of heat between two liquids, chemical reaction between two liquids, and sometimes simultaneous chemical reaction and liquid extraction, or even simultaneous reaction, heat transfer, and extraction. Devices embodying this invention may be constructed which are admirably suited for the accomplishment of any or all of these things.

Apparatus provided by the invention comprises a plurality of superimposed decks in vertical alignment forming a column having a vertical partition which divides each deck into a mixing compartment and a settling compartment which together constitute a stage. Communicating ports are provided in the vertical partition of each deck between the mixing compartment and the settling compartment whereby the heavier liquid passes from the settling compartment of each given deck to the mixing compartment of the deck immediately below that given deck and the lighter liquid passes from the settling compartment of that given deck to the mixing compartment of the deck immediately above that given deck. Means are also provided for mixing the lighter and heavier liquids intimately in each mixing compartment. Ports are provided in the vertical partition between the compartments of each deck for the passage of the liquids in mixed condition from the mixing compartment of a deck to the settling compartment of that deck and, if desired, ports may be provided in the partition for passage of heavier liquid or lighter liquid selectively from the settling compartment of each deck to the mixing compartment of that deck. And valve means are provided which may be adjusted to vary the effective areas of said ports. The top deck is provided with conduit means for introducing the heavier liquid into the column which works its way downwardly through the column and conduit means for withdrawing the lighter liquid which has worked its way upwardly through the column. The bottom deck is provided with conduit means for introducing the lighter liquid into the column and with conduit means for withdrawing the heavier liquid which has worked its way downwardly through the column.

Although the novel features which are believed to be characteristic of the invention are pointed out in the annexed claims, the invention itself, as to its objects and advantages, and the manner in which it may be carried out, may be better understood by reference to the following more detailed description taken in connection with the accompanying drawings forming a part hereof, in which:

3,325,255 Patented June 13, 1967 FIG. 1 is a perspective view from one side of the vertical partition wall of a liquid extractor embodying the invention, with parts broken away to show the internal construction;

FIG. 2 is a perspective view of the apparatus shown in FIG. 1 from the other side of the vertical partition, with parts broken away, and showing a typical mixer compartment;

FIG. 3 is a view in elevation looking from the mixing compartment side toward the vertical partition and showing the valves and ports in the verticalpartition, taken on line 3-3 of FIG. 4;

FIG. 4 is a sectional FIG. 3;

FIGS. 5 and 6 are views showing details; and

FIGS. 7, 8 and 9, are diagrammatic views to illustrate modified forms.

Referring now to the drawings in which like reference characters denote like parts throughout the several views, the extractor apparatus comprises a plurality of superimposed decks a, b, c, d, and e, to form a column which, as shown, is rectangular in plan. Side walls 4, 8, front wall 9, rear wall 7, top wall 5, and bottom wall 6, enclose the column. The top deck a and bottom deck e are somewhat diiferent in construction from the decks b, c, d, therebetween; these latter decks being the same in construction in all respects.

As shown, there are three intermediate decks, namely, b, c, d, but a larger or smaller number of intermediate decks may be employed, depending on the nature of the operation that is to be performed. Each deck provides a stage, i.e. an arrangement which brings the liquids into contact, mixes them intimately, and separates them. Hence, the apparatus, as shown, is a multistage extractor in that it repeats the steps of bringing the liquids into contact, intermixing them, and separating them, as the liquids pass through the column, the lighter liquid working its way upwardly through the column and'the heavier liquid working its way downwardly through the column.

The apparatus shown in the drawings consists of five stages: a, b, c, d, 2. Each stage includes a mixing zone and a settling zone. The top deck a comprises a mixing zone or compartment 10a and a settling zone or compartment 11a. The bottom deck e comprises a mixing zone or compartment 10c and a settling zone or compartment 11e. Intermediate decks b, c, d, each comprises respectively a mixing zone 10b, 10c, 10d and a settling zone 11b, 11c, 11d; it being noted that a partition 12a, b, c, d, e, separates the respective decks into mixing and settling compartments; thus providing superimposed mixing compartments or zones'ltla, b, c, d, e, in vertical alignment and settling compartments or zones 11a, b, c, d, e, in vertical alignment, the individual partitions 12a, b, c, d, e, being in vertical alignment; thus providing a vertical partition 12 through the column of decks.

. Each of the partitions 12a, b, c, d, e, is provided with numerous ports. Inasmuch as each of these deck partitions is similar to the others, reference is made to partition 12b in deck b which may be considered as typical. A port 13b, herein called a heavy liquid port, is located in the upper portion of partition 12b and below the floor 14a of deck a. This port communicates with a downcomer passageway 16b through a floor opening 15a in the floor 14a on the settling side of partition 12. This passageway 16b is defined by spaced sidewall plates 17b, 18b, and curved plate 19b. Now it will be seen that heavy liquid which settles in the bottom of settling compartment 11a may pass from this compartment through floor opening 15a, through downcomer passageway 16b into the mixing compartment 10b of deck b. A vertically adjustable slide valve comprising gate 20b, described in further detail hereinafter, may be adjusted to open and close port 13b plan view taken on line 4-4 of or to any position therebetween for the purpose of regulating the effective flow area of port 13b. Each of the decks have a similar downcomer passageway and valve arrangement. They are designated in the drawings by the same reference numeral having an appropriate sub-letter; a, b, c, d, or :2. Gates 20a, b, c, d, e, are secured to a common rod or stem 45 extending vertically through suitable bores in the deck floors and top wall 5. The rod is slidably mounted in the bores. The top end portion of the valve rod 45 extends through a packing gland 46 in top wall 5 (see FIG. 6). A clamp ring 47 rests on the packing gland. This clamp ring may be clamped to the rod 45 by a set screw 48 in vertically adjusted position for proper registry of the various gates a, b, c, d, e, with their respective ports in the partition 12. It may be observed here that each gate may be clamped to the rod 45 in desired vertical adjusted position by means of a set screw 48.

A port 21b, herein called a light liquid port, is located in the lower portion of partition 12b and above the floor 14b of deck b. This port communicates with a riser passageway 22b through'floor opening 23b in fioor 14b of deck b on the settling side of partition 12.

This passageway 22b is defined by sidewall plates 25b, 26b, and curved plate 27b. Thus, light liquid which rises to the top in settling Zone 110 may pass from this compartment through floor opening 23b in floor 14b through riser passageway 22b into the mixing compartment 10b of deck b. A vertically adjustable slide valve comprising gate 28b, described in further detail hereinafter, may be adjusted to open and close port 21b, or to any position therebetween for the purpose of adjusting the effective flow area of port 21b. Each of the decks is provided with similar riser passageways 22a, b, c, d, e; and similar gate valves 28a, b, c, d, e. All of these gates are adjustably secured to a common rod or stem 49 extending vertically through bores, in the deck fioor and top wall 5. The rod 49 extends through a packing gland 50 and a ring 51 clamped to the rod rests on the packing gland 50 in the same manner as valve rod 45.

Midway between deck floors 14a and 14b in the rear portion of partition 12b there is a port 30b, herein called a mixed liquid port for convenience of description. This port 30b communicates with a horizontal passageway 31b, in the form of a horizontally disposed tunnel, the discharge end 32b of which terminates in the settling compartment 11b at about midway between partition 12 and sidewall 4. The horizontal passageway 31b is defined by tunnel walls 33b, 34b, 35b, and rear wall 7. Heavy and light liquids intermixed in mixing compartment 10b may flow as a mixture from .this mixing compartment 10b through port 30b and tunnel 31b into settling compartment 11b.

Each of the decks is provided with a similar port 30a, b, c, d, e, and horizontal passageway or tunnel 31a, b, c, d, 2.

Two recycle ports b and 41b are provided in partition 12b. One recycle port 40b for recycling lighter liquid from settling compartment 11b back to mixing compartment 10b is located in partition 12b in its upper portion and below deck floor 14a. Another recycle port 41b for recycling heavier liquid from settling compartment 11b back to mixing compartment 10b is located in partition 12b in its lower portion and above deck floor 14b. Valve means comprising a vertically movable slide gate 42b is provided for opening and closing port 40b. This gate is adjustable in any position between full open and full close for adjusting the effective flow area of port 40b and it is located on the mixing compartment side of partition 12b. Similar valve means comprising gate 43b is provided for opening and closing port 41b and for adjusting the effective flow area of port 41b. Gate 43b is located on the settling compartment side of partition 12b. Each deck is provided with similar ports 40a,

b, c, d, e, and gates 42a, b, c, d, e. These valve gates 42a, b, c, a, e, are secured to a common vertically disposed rod or stem 53 and mounted in the same manner of the valve gates 20a, b, c, d, 2. Each deck is provided with similar ports 41a, b, c, d, e, and similar gate valves 42a, b, c, d, e. These gates are secured .to a common vertically mounted rod or stem 55 in the same manner as valve gates 20a, b, c, d, e. These recycle ports and gates are not necessary in some operations of the multistage column and in such instances may be dispensed with.

Each mixing compartment 10a, b, c, d, e, is provided with an agitator or rotary mixing device operative to cause one of the liquids to be dispersed in the other as the heavier and lighter liquids pass through the respective mixing compartments. And each mixing compartment is provided with means for influencing the direction of flow of the mixed liquids .toward and through its communicating mixed liquid tunnel. As shown, the agitator device for each of the mixing compartments is in the form of a rotatable stirring wheel having circumferentially spaced, radially disposed fiat impeller blades, mounted for rotation in the mixing compartment.

Inasmuch as the impeller wheels are similar and similarly mounted, reference is made to mixing compartment b as typical. The impeller wheel 60b comprises a hub portion 61b having a bore through which an axle shaft 59 extends. The hub is keyed to the shaft. A fiat disk 62b is secured to .the hub and consequently rotates with shaft 59. Circumferentially spaced, vertically and radially disposed, flat impeller blades 63b are fixed to the disk; the structure being in a form similar to a paddle wheel, herein referred to as an impeller wheel. This impeller wheel serves as a mechanical stirring, mixing and liquid dispersion device which may be rotated at any desired rotary speed. Each of .the impeller wheels 60a, b, c, d, e, is mounted on the common shaft 59 which extends through the top wall 5 of the column. The lower end of shaft 59 rotates in a thrust bearing 64 carried on deck floor 14e. The upper end of shaft 59 extends through .top wall 5 and is rotatable in a bearing provided with a packing gland 65 which is mounted in a disk plate 66 removably secured to the top wall 5 of the column. The top wall is provided with a circular opening 67 which the plate 66 covers. Deck floors 14a, b, c, d, are provided with a similar opening. Mounted on the shaft at each deck floor level is a disk plate 68a, b, c, d, and x, which is rotatable in its registering floor opening 67a, b, c, d, and substantially closes the registering floor opening. This arrangement permits the shaft 59 together with all the agitator wheels 60a, b, c, d,'e, and disks 68a, b, c, d, x, to be removed from the column by removing cover plate 66. Means are provided to rotate shaft 59 and hence the agitator wheels 60a, b, c, d, e, at any desired speed. Such means are shown conventionally in the drawings as an electric motor 70 having a shaft pulley over which is trained an endless drive belt 71, in turn trained over a pulley 72 keyed to shaft 59.

Means, comprising baffles, are mounted in each of the mixing compartments to influence the direction of flow of .the liquids passing through them. The baffles are so arranged that the rotational motion of the impeller wheel in the mixing compartment produces a larger pressure at the mixed liquid port to force the mixed liquids through the tunnel to the settling compartment than the pressure at the other ports through which liquids enter the mixing compartment. The impeller wheel thus acts as a pump, in addition to serving its other purposes of mixing and dispersing of the liquids of different densities. The advantageous result is that substantial additional force is available to cause flow of liquids through the column besides the force of gravity acting upon the liquids. Consequently, .the pumping action of the impeller Wheels in the mixing compartments is utilized in each stage to add a force to the force of gravity to overcome pressure drop resulting from the flow of the liquids. This is brought about deliberately and purposefully by .the arrangement of the impeller wheel, the baffles in the mixing zone, and the arrangement of the inlet and outlet ports in the partition between the mixing and settling compartments.

Inasmuch as the bafile arrangement in each of the decks a, b, c, d, e, is the same, reference is made to deck b as typical. A bafile 81b, herein for convenience of description called a heavy liquid bafile, is mounted on partition 12b and extends vertically from deck floor 14a to deck floor 14b. In plan view (see FIG. 4) the battle has a panel 82b the inner vertical edge of which is secured to the vertical partition 12b with panel 82b in a vertical plane at right angles to the vertical plane of the partition. This baffle is formed to have an intermediate panel 83b at an angle to panel 82b and is then turned inwardly to provide a third panel 84b which lies in a vertical plane parallel with the plane of the partition, so that the free vertical edge 85b of the bafile 81b is at about midway of the width of the heavy liquid port 13b.

Bafile 86b opposite light liquid port 21b has a panel 87b similar to panel 82b and a panel 88b extending outwardly therefrom at an angle. This baffle is referred to herein for convenience of description as a light liquid baffle. It, like baffle 81b, extends the full height of the deck and it is secured at its inner edge to partition 12b. The outer free vertical edge 8% is positioned at about midway of the width of the light liquid port 21b.

Bafiie 90b for the recycle ports 40b and 41b, has a panel 91b similar to panels 81b and 82b and a panel 92b extending outwardly therefrom at an angle. It is herein referred to as a recycle baffle and it, also, extends the full height of the deck and is secured at its inner edge to partition 12b. The outer free vertical edge 93b is positioned at about midway of the width of the recycle ports 40b and 41b.

Now it will be seen that when impeller wheel 60b is rotating in the direction of arrow 94 (see FIG. 4), liquids flowing into mixing compartment 10b from settling compartment 11a and from settling compartment lie, or recycle liquids fiowing from compartment 11b, will be influenced to flow in a direction about the outer periphery of the mixing compartment toward the outlet port 30b and through tunnel 31b into the settling chamber 11b; the baffles tending to defiect and direct the moving liquids in that general path of travel in the mixing compartment 10b.

A conduit 73, having an openable and closable valve 74 extends through top wall 5 into passageway 16a for introducing heavier liquid into mixing compartment 10a. A conduit 75 having an openable and closable valve 76, extends from settling compartment 11a through top wall 5, through which lighter liquid settling upwardly in the settling zone 11a is removed from the column.

A conduit 77 communicating with passageway 22e, having an openable and closable valve 78, extends through bottom wall 6, through which lighter liquid may be introduced into mixing compartment 102. A conduit 79, having an openable and closable valve 80, communicates with settling compartment lle through which heavy liquid may be removed from the column.

The column may, if desired, be provided with gage glasses at each stage; one such gage 24b being shown as illustrative. Such a gage glass is useful for visually determining the interface between the settling liquids within the settling compartment 11b. Draw otf cocks, such as cock 25c, may be provided for each stage to draw liquid from each stage.

FIGS. 7, 8, 9, illustrate, in schematic or diagrammatic fashion, modified forms of apparatus which are within the contemplation of the invention. These figures represent plan views, the sidewalls of the column being indicated by reference numeral the settling compartment by 101; mixing compartment by 102; the impeller wheel 103; the partition separating the mixing compartment from the settling compartment being indicated by 101; the heavy and light liquid ports by 105, 106, and their gate valves by 107, 108; recycle ports and their valves by 109, 110; the mixed liquid port 111 from mixing chamber 102; the tunnel from the mixing chamber to the settling chamber by 112; and the bafiies by 113, 114, 115.

To illustrate one manner of operating the liquid extractor the following mode of operation may be considered as representative. During operation, the entire column is normally filled with the liquids to be contacted, and no air or gas space is normally present. However, if its is desired, for example, to operate the multistage extractor at a pressure higher than atmospheric, the outlet conduit 75 may be positioned at the sidewall of the top deck and a body of air or inert gas may be maintianed above the outlet under any desired pressure above atmospheric to place the liquids in the column below the gas at such desired higher pressure.

The operation of the apparatus shown will be described, for illustrative purposes, as if it were being used to carry out a single-solvent extraction. Two liquids, one, a feed stock whose constituents are to be separated, and the other, an extracting solvent, are continuously fed into the top and bottom of the column. The liquids must be immiscible, or substantially immiscible, and must have different densities. Since the feed may be relatively the lighter or heavier of the two, and the solvent the lighter or the heavier of the two, the operation will be described in terms of light and heavy liquids.

Light liquid is continuously introduced through conduit 77 and after flowing upwardly through the column, leaves through conduit 75. Heavy liquid is introduced through conduit 73, passes downwardly through the column and leaves through conduit 79.

Light liquid entering through conduit 77 passes into and through riser passageway 226, through port 212 into the mixing compartment ltle of the first (or lower-most) stage e, where it is mixed with heavy liquid flowing from settling compartment 11d of the next higher (or second) stage through downcomer passageway 162 through port 1312 in partition 12a. The rotary action of rotating impeller 60a of the first stage disperses one of the liquids into very small droplets surrounded by the other liquid which remains as a continuous phase. The many very small droplets produce a large interfacial area between the two liquids and a high level of tubulence in the continuous liquid is produced by the action of the impeller 60c. These both lead to high rates of extraction of the extractible constituents of the feed into the solvent. The dispersion of the droplets and continuous liquid thus produced in the mixing compartment. flows through port 302 from the mixing compartment, through tunnel 31e into settling compartment Me of the first stage e. Here the larger cross-sectional area and absence of stirring produces conditions permitting coalescence of the droplets into bulk liquid because of their different densities, the light liquid rising to the upper part while the heavy liquid settles to the bottom part of settling compartment 11e, a horizontal interface being maintained between the liquids at a place between the ceiling and floor of the deck. The heavy liquid thus having passed through the bottom-most stage 2 and being clarified of entrained light liquid in settling compartment He, leaves the extractor through conduit 79.

The light liquid, clarified of entrained heavy liquid in settling compartment lle, proceeds to the second stage d through riser passageway 22d through port 21a (in partition 12d) which leads it to the mixing compartment of the second stage at. In mixing compartment 10d, the light liquid is contacted (as in the mixing compartment of the first stage) with heavy liquid which passes through downcomer passageway 16d from settling compartment 110 of the third stage 0. Again a dispersion is formed in mixing compartment 10d conducive to rapid extraction by the stirring action of impeller 60d; the dispersion leaving the mixing compartment 10d and passing through port 30d thence through tunnel 31d from which it fiows into the settling compartment 11d of the second stage d. Here the droplets of dispersed liquid again coalesce into a bulk; the light liquid settling to the top and the heavy liquid to the bottom of settling compartment 11d of the second stage d. A horizontal interface between the liquids is maintained at a suitable level; preferably, but not necessarily, midway between the deck floors. The heavy liquid flows from settling compartment 11d into mixing compartment 10a of the first stage e through downcomer passageway 16c through port 136 and the light liquid from compartment 11d flows through riser passageway 220 through port 21c to the mixing compartment of the third stage 0.

In similar fashion the liquids flow counter-currently from stage to stage (i.e. successively through the five stages of the column, as shown), the lighter liquid working its way upwardly from the bottom to the top of the column through successive stages and the heavier liquid working its way downwardly from the top to the bottom of the column in successive stages, the two liquids being mixed (dispersed one in the other) in the mixing compartments and settled from each other in the settling compartments in successive stages, i.e. through successive decks e, d, c, b and a. And it may be noted here that the arrangement of mixing compartment and settling compartment of the same stage, as shown, provides for flow of the clarified liquids to their respective next stages. This avoids back mixing which has been a drawback in many prior art liquid extractor devices.

In the settling compartment 11a of the top-most, or fifth, stage, the light liquid is settled from the heavier liquid for the last time, and flows in clarified form, free from entrained heavy liquid, out of the extractor through conduit 75. The heavy liquid enters the mixing compartment 10e of the top-most stage through conduit 73 and is settled from the lighter liquid for the last time in settling compartment He and flows in clarified form, free from entrained lighter liquid, out of the extractor through conduit 79.

Attention is directed particularly to light liquid recycle ports 40a, 17, c, d, e, and heavy liquid recycle ports 41a, b, c, d, e. These ports may be dispensed with in certain kinds of operation and in some either one or the other may be utilized. However, in the preferred embodiment in which both the light liquid recycle ports and the heavy liquid recycle ports are present together with their valves, they are advantageous and serve very desirable purposes. The upper ports 40a, b, c, d, e, serve to permit flow of some of the settled light liquid to flow back to the same mixing compartment or zone from which it last emerged (the same stage) and the lower ports 41a, b, c, d, e, permit flow of some of the heavy liquid back to the mixing zone of the same stage. This return flow, herein called recycle, is advantageous in many instances. Coalescense and settling of some dispersions are much more rapid (or completed in less time) if one of the liquids rather than the other is dispersed. Whether the liquid thus to be dispersed enters the column in the minority or the majority, it may be dispersed at will in any desired proportions up to the limit imposed by nature, independently of the intensity of agitation.

It can be shown theoretically that, under certain circumstances, important improvement in stage efiiciency or height equivalent to a theoretical stage can be accomplished by recycling one or the other of the liquids. This can be done at will by manipulation and adjustment of the apparatus disclosed herein. The valve gates 42a, b, c, d, e, may be raised or lowered by raising or lowering the common stem 53 to which they are adjustably secured and 8 each individually may he vertically adjusted on the stem. Hence, the effective flow area of each of the light liquid recycle ports a, b, c, d, e may be controlled as desired to cause more or less light liquid to be recycled in each of the different stages. The same applies to the valve gates 43a, [2, c, d, e, secured to common stem 55 to which they are adjustably fixed so that the effective flow area of each of the heavy liquid recycle ports 41a, b, c, d, e, may be adjusted to control the amount of heavy liquid recycled in each of the different stages.

By means of the recycling provisions it is also possible to make that liquid which has been dispersed, converted to a continuous liquid in all mixing compartments of the various stages without interrupting the operation of the extractor. This may be done by recycling temporarily a relatively large quantity of the dispersed liquid, so that its volume in the mixing zone becomes sufficiently larger, say seventy-five percent of the total. The inversion will then occur. That is, the liquid which was continuous will become the dispersed one, and that which was dispersed will become the continuous one in the mixing zone.

The sliding valve gates 29a, b, c, d, e, for heavy liquid ports 13a, b, c, d, e, are adjustably secured to common stem 45 and the sliding valve gates 28a, 1), c, d, e, for light liquid ports 21a, 1), c, d, e, are adjustably secured to common stem 49. Hence the efiective flow areas of these ports may be adjusted in similar manner as the effective flow areas of ports 40a, b, c, d, e, and ports 41a, 1), c, d, e. Thus the pressure drop for the flow of the liquids from stage to stage may be controlled. Also by changing the effective flow of areas of ports 13a, b, c, d, e, and 21a, b, c, a, e, the position of the horizontal interface between the settled liquids in the settling compartments or zones may be controlled and regulated. By this means the interface may be maintained near midway between the deck floors; or, if the coelescing and settling characteristics of the liquids require, the interface may be maintained at a higher or lower position in the settling zones.

It may be observed here that the valve stems 45, 49, and 53, as well as the rotary shaft 59 extend through packing glands, thus to make the housing of the column leak proof. Also, if desired, the mixed liquid ports 30a, b, c, d, e, may be equipped with valve gates secured to a common stem extending through the top wall 5 in the same manner as stem 45, for example; thus to provide means for adjusting and controlling the efiective flow areas of these ports.

The pumping action of the impeller wheels 60a, b, c, d, e, in their respective mixing compartments is very advantageoues. This pumping action is brought about largely by the baffles 81a, 11, c, d, 6; 86a, b, c, d, e, and 90a, b, c, d, e. Tests have shown that an arrangement such as that disclosed adds a materially greater force to the force of gravity to overcome pressure drop resulting from the flow of the liquids. The pressure developed at the mixed valve ports 30a, b, c, d, e, where the dispersion passes and thence through the tunnels 3101, b, c, d, e, is substantially greater than at the inlet ports 13a, b, c, d, e, and 21a, b,

c, d, e, for the heavy and light liquids and the recycle ports 40a, b, c, d, e, and 41a, b, c, d, e, and this outlet pressure from the mixing compartments may be controlled within limits by the speed of rotation of the impeller wheels; a higher speed developing a higher pressure to assist the force of gravity to cause flow of the liquids through the extractor. The pressures are developed at the places which favor flow of the liquids in the desired directions.

The terms and expressions which have been employed herein are used as terms of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed.

What is claimed is:

1. Apparatus for contacting liquids of different densities which are incompletely miscible which comprises a plurality of superimposed decks forming a vertical column of decks;

a vertical partition in each of said decks dividing each deck to provide a mixing compartment and a settling compartment thereby providing a stage in which said liquids may be contacted and mixed in a mixing zone and settled and separated in a settling zone at each deck;

first, second, and third ports in each partition of each deck, located adjacent the bottom, the top and approximately halfway between the top and bottom of each partition respectively;

a riser passageway connecting the top, adjacent the partition means, of each of said settling compartment with the first port in the partition of the next higher deck thereby connecting each of said settling compartments with the mixing compartment of the next higher deck;

a downcomer passageway connecting the bottom, adjacent the partition means, of each of said settling compartments with the second port in the partition of the next lower deck to connect each of said settling compartments with the mixing compartment of the next lower deck;

a horizontal passageway connecting each of said settling compartments with the third port in the partition of that same deck thereby connecting each of said mixing compartments with the settling compartment of the same deck and extending from said third port into said settling compartment to a point substantially beyond the riser passageway and downcomer passageway from said settling chamber and preventing mixed liquids passing through said third port from passing lirectly out said riser and downcomer passages from the settling compartment;

rotatable impeller wheel agitator means in each of said mixing compartments each of said impeller wheels secured to a power driven vertically mounted, common rotatable shaft, operative to intimately intermix light liquid and heavy liquid passed into said mixing compartments through said light liquid ports and said heavy liquid ports;

means for introducing heavy liquid to the top portion of the uppermost mixer compartment of said column and means for withdrawing heavy liquid from the bottom portion of the lowermost settler compartment of said column; and i means for introducing light liquid into the bottom por tion of the lowermost mixer compartment of said column and means for withdrawing light liquid from the top portion of the uppermost settler compartment of said column;

fourth and fifth ports in eachof the partitions of each deck, the fourth ports being positioned in the top portion of said partition to recycle light liquid from the settling compartment of its deck back to the mix ing compartment of the same deck and the fifth ports being positioned in the bottom portion of said partition to recycle heavy liquid from the settling compartment of its deck back to the mixing compartment of the same deck.

2. Apparatus according to claim 1 which includes valves for each of said first and second ports adjustable to vary the effective flow areas of said first and second ports, valves for each of said fourth ports adjustable to vary the effective flow areas of said fourth ports and valves for each of said fifth ports adjustable to vary the effective flow areas of said fifth ports.

3. Apparatus according to claim 2 which include a first stem mounted for vertical movement to which all of the valves for said first ports are secured, a second stem mounted for vertical movement to which all of the valves 10 for said second ports are secured, a third stem mounted for vertical movement to which all of the valves for said fourth ports are secured, and a fourth stem mounted for vertical movement to which all of the valves for said fifth ports are secured.

4. Apparatus for contacting liquids of different densities which are incompletely miscible which comprises a plurality of superimposed decks forming a vertical column of decks; a vertical partition in each of said decks dividing each deck to provide a mixing compartment and a settling compartment providing a stage in which said liquids are contacted and mixed in a mixing zone and settled and separated in a settling zone; a riser passageway connecting each of said settling compartments with the mixing compartment of the next higher deck and providing a light liquid port in the upper portion of each deck through which light liquid passes from the settling compartment of each deck into the mixing compartment of the next higher deck; a downcomer passageway connecting each of said settling compartments with the mixing compartment of the next lower deck and providing a heavy liquid port in the lower portion of each deck through which heavy liquid passes from the settling compartment of each deck into the mixing compartment of the next lower deck; a passageway through the partition of each deck connecting the mixing compartment of each deck with the: settling compartment of that deck and providing a mixed liquid port vertically intermediate the heavy and light liquid ports through which mixed liquid passes from the mixing compartment of each deck to the settling compartment of that deck; a rotatable wheel agitator means in each of said mixing compartments operative to intimately intermix light liquid and heavy liquid passe-d into said mixing compartments through said light liquid ports and said heavy liquid ports; a vertical rotatable shaft extending through said mixing compartments to which each of said agitator wheels is fixed and rotating all of said agitator means in unison upon rotation of said shaft; power means connected to rotate said shaft; a passageway in the upper portion of each deck connecting the settling compartment of that deck with the mixing compartment of the same deck and providing a light liquid recycle port through which light liquid passes from the upper portion of the settling compartment of that deck back to the mixing compartment of that deck; a passageway in the lower portion of each deck connecting the settling compartment of that deck with the mixing compartment of that deck and providing a heavy liquid recycle port through which heavy liquid passes from the lower portion of the settling compartment of that deck back to the mixing compartment of that deck; valve means for each of said light liquid, heavy liquid, and recycle ports operative to adjust and control the flow of liquid through each of said light liquid, heavy liquid, and recycle ports; a first vertical shaft accessible from outside of said column to which the valve means for the heavy liquid ports are fixed for operating these valve means in unison; a second vertical shaft accessible from outside of said column to which the valve means for the light liquid ports are fixed for operating these valve means in unison; a third vertical shaft accessible from outside of said column to which the valve means for the heavy liquid recycle ports are fixed for operating these valves means in unison; a fourth vertical shaft accessible from outside of said column to which. the valve means for the light liquid recycle ports are fixed for operating these valve means in unison; bafiie means mounted in each of said mixing compartments adjacent the passageways connecting said mixing compartments and settling compartments and positioned to cause a higher pressure on the liquids in the mixing compartment at the mixed liquid port through which mixed liquids pass from each mixing compartment of each deck into the settling compartment of that deck than the pressure on the liquids at the ports where the heavy and light liquids enter into the mixing compartment of that deck so that said wheel agitator means moves the inter-mixed liquid from the mixing compartment of each deck through its mixed liquid port by a pumping action; means for introducing heavy liquid to the top portion of said column; means for withdrawing heavy liquid from the bottom portion of said column; means for introducing light liquid into the bottom portion of said colu-mn and means for withdrawing light liquid from the top portion of said column.

5. Apparatus according to claim 4, in which said baffle means in each mixing compartment comprises three bafile plates, each having one of its vertical edges engaging the interior surface of the wall defining the mixing compartment space and each plate extending into said space but terminating short of the agitator wheel, one of said baffie plates being positioned adjacent the mixed liquid port, another of said baflle plates being positioned adjacent the heavy liquid port and the other of said baffle plates being positioned adjacent the light liquid port.

6. Apparatus for contacting liquids of diiferent densities which are incompletely miscible which comprises a plurality of superimposed decks forming a vertical column of decks; a vertical partition wall in each of said decks dividing each deck to provide a mixing compartment and a settling compartment thereby providing a stage in which said liquids may be contacted and mixed in a mixing zone and settled and separated in a settling zone at each deck; light liquid, heavy liquid and mixed liquid ports adjacent the partition Wall of each deck, located respectively adjacent the bottom, the top and approximately halfway between the top and bottom of each deck; a riser passageway adjacent the partition wall of each deck connecting the top portion of each of said settling compartments through the light liquid port of each deck with the next higher deck thereby connecting each of said settling compartments with the mixing compartment of the next higher deck; a downcomer passageway adjacent the partition wall of each deck connecting the bottom portion of each of said settling compartments through the heavy liquid port of each deck with the next lower deck to connect each of said settling compartments with the mixing compartment of the next lower deck; a passageway in the partition wall of each deck connecting each of said settling compartments through the mixed liquid port in the partition wall of each deck with the setting compartment of the same deck, thereby connecting each of said mixing compartments with the settling compartment of the same deck; rotatable impeller wheel agitator means in each of said mixing compartments, each of said impeller wheels secured to a power driven vertically mounted, common rotatable shaft, operative to intimately intermix light liquid and heavy liquid passed into said mixing compartments through said light liquid ports and said heavy liquid ports; means for introducing heavy liquid to the top portion of the uppermost mixer compartment of said column and means for withdrawing heavy liquid from the bottom portion of the lowermost settler compartment of said column; and means for introducing light liquid into the bottom portion of the lowermost mixer compartment of said column and means for withdrawing light liquidfrom the top portion of the uppermost settler compartment of said column; a light liquid recycle port adjacent the partition wall of each deck, positioned in the top portion of each deck to recycle light liquid from the settling compartment of its deck back to the mixing compartment of the same deck; a heavy liquid recycle port adjacent the partition wall positioned in the bottom portion of each deck to recycle heavy liquid from the settling compartment of its deck back to the mixing compartment of the same deck; valve means for each of said light and heavy liquid ports and each of said light and heavy recycle ports to vary the effective flow areas of these ports; bafiles in each of said mixing compartments mounted adjacent said ports and arranged to influence the flow of liquids in the mixing compartments to cause a higher pressure on the mixed liquid in the mixing compartment at the mixed liquid port through which mixed liquid passes from the mixing compartment of each deck than the pressure of the liquids at the ports where the heavy and light liquids enter into that mixing compartment so that the agitator wheel moves the liquids through the mixing compartments by pumping action.

7. Apparatus according to claim 6, in which said baffle means in each mixing compartment comprises three vertically mounted baffle plates, each having one of its vertical edges engaging the interior surface of the wall defining the mixing compartment space and each plate extending into said space but terminating short of the agitator Wheel, one of said bafile plates being positioned adjacent the mixed liquid port, another of said baffle plates being positioned adjacent the heavy liquid port and the other of said baffle plates being positioned adjacent the light liquid port.

References Cited UNITED STATES PATENTS 1,297,171 3,1919 Holley 23-270 X 2,201,550 5/1940 Van Dijck 23-2705 X 2,290,980 7/1942 MacLean 23-2705 X 2,646,346 7/1953 Coplan 23-2705 2,743,999 5/1956 Bi'nswanger 23-310 2,754,179 7/1956 Whatley 23-2705 2,778,717 1/1957 Decker 196-1452 X 2,845,936 8/1958 Boynton 23-270 X 2,851,396 9/1958 Myers 23-2705 X 3,083,126 3/1963 Grifilths 23-310 X 3,206,288 9/1965 Hazen 23-310 FOREIGN PATENTS 955,603 7/1949 France.

NORMAN YUDKOFF, Primary Examiner.

S. I. EMERY. Assistant Examiner. 

1. APPARATUS FOR CONTACTING LIQUIDS OF DIFFERENT DENSITIES WHICH ARE INCOMPLETELY MISCIBLE WHICH COMPRISES A PLURALITY OF SUPERIMPOSED DECKS FORMING A VERTICAL COLUMN OF DECKS; A VERTICAL PARTITION IN EACH OF SAID DECKS DIVIDING EACH DECK TO PROVIDE A MIXING COMPARTMENT AND A SETTLING COMPARTMENT THEREBY PROVIDING A STAGE IN WHICH SAID LIQUIDS MAY BE CONTACTED AND MIXED IN A MIXING ZONE AND SETTLED AND SEPARATED IN A SETTLING ZONE AT EACH DECK; FIRST, SECOND, AND THIRD PORTS IN EACH PARTITION OF EACH DECK, LOCATED ADJACENT THE BOTTOM, THE TOP AND APPROXIMATELY HALFWAY BETWEEN THE TOP AND BOTTOM OF EACH PARTITION RESPECTIVELY; A RISER PASSAGEWAY CONNECTING THE TOP, ADJACENT THE PARTITION MEANS, OF EACH OF SAID SETTLINE COMPARTMENT WITH THE FIRST PORT IN THE PARTITION OF THE NEXT HIGHER DECK THEREBY CONNECTING EACH OF SAID SETTLING COMPARTMENTS WITH THE MIXING COMPARTMENT OF THE NEXT HIGHER DECK; A DOWNCOMER PASSAGEWAY CONNECTING THE BOTTOM, ADJACENT THE PARTITION MEANS, OF EACCH OF SAID SETTLING COMPARTMENTS WITH THE SECOND PORT IN THE PARTITION OF THE NEXT LOWER DECK TO CONNECT EACH OF SAID SETTLING COMPARTMENTS WITH THE MIXING COMPARTMENT OF THE NEXT LOWER DECK; A HORIZONTAL PASSAGEWAY CONNECTING EACH OF SAID SETTLING COMPARTMENTS WITH THE THIRD PORT IN THE PARTITION OF THAT SAME DECK THEREBY CONNECTING EACH OF SAID MIXING COMPARTMENTS WITH THE SETTLINE COMPARTMENT OF THE SAME DECK AND EXTENDING FROM SAID THIRD PORT INTO SAID SETTLING COMPARTMENT TO A POINT SUBSTANTIALLY BEYOND THE RISER PASSAGEWAY AND DOWNCOMER PASSAGEWAY FROM SAID SETTLING CHAMBER AND PREVENTING MIXED LIQUIDS PASSING THROUGH SAID THIRD PORT FROM PASSING DIRECTLY OUT SAID RISER AND DOWNCOMER PASSAGES FROM THE SETTLING COMPARTMENT; ROTATABLE IMPELLER WHEEL AGITATOR MEANS IN EACH OF SAID 